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Laars Endurance Help Advice What Next?

I have a Laars EBP 110 endurance combo unit. It is about 6-7 years old. Just moved into the house about a year ago and noticed issues in the showers or faucets and depending on the time of year, for some reason, summer being the worst, we would get intermittent cool showers. Got to a point where we could time when the cold/cool water would hit. Would run in like 30 second cycles.

Fast forward through a couple plumber calls, Laars tech calls and some DIY googling and I am at my wits end. I've replaced the following

1. Mixing Valve (watts 70a)

2. Water Flow Switch (as recommended)

3. Heat Exchanger (what a pain in the ass that was)

After all these tweaks, it would get marginally better but then back to cycling hot/cold water. The unit has no problem getting up to temp. Firing up on demand. Delivering hot water in a reasonable period of time. It just can't sustain it for a 5-10 minute shower with no other hot water running. I've tested through all of the showers and faucets in the house with thermometer and can record up to a 15-20 degree swing in temp without touching the faucet itself. The last plumber said it was time to cut bait.

Not sure where else to turn but to a new unit - not sure what's out there that won't break the bank - a direct replacement runs about 2500 bucks really not looking forward to replacing it with the same.....Maybe the folks from Laars who post here from time to time might help?

Sorry I used that old saying - fish or cut bait. I guess I've been fishing too much!

I will get some pics as soon as I get home tonight and post them. Other than this issue - we haven't really had any problems getting the house to temp on the t-stat, so I assume that its isolated to the DHW side?

Some more info on the mixing valve - I had two plumbers take a look at this and they both said that the mixing valve appears to be working properly. I replaced the "guts" to see if it would help, didn't sweat a brand new one in. Basically asked the plumbers to do it and they said it would be a waste of money because they think it works just fine.

I'd say being in the northeast (RI) the water is a little hard and I've seen evidence of the buildup on both the mixing valve and water flow switch. Not so much the heat exchanger, it actually looked ok on the inside.

Any other pics you think that would help? I will try my best. Thanks again!

The IR will work OK if you wrap electrical tape on the pipe. It takes a bit of practice to get reasonably accurate readings. It helps to hold the gun a few inches away and move it until you get the highest reading.

Carl

"If you can't explain it simply, you don't understand it well enough"Albert Einstein

Are you on well or city water? If you are on a well, you are probably getting pressure fluctuations that the mixing valve cannot compensate for. The timing thing may be when the tank pressure drops enough that the well pump kicks on?

when we first moved in - it was much worse. IT was random cold water spells but for much much longer periods of time and the only fix it seemed was to keep turning the faucet on and off until it magically got warm again, if at all. This issue seemed to dissipate after the heat started going on and the colder weather came (moved in sept 12)

After a few months of hearing the wife barking about her cold showers, I replaced the mixing valve guts and that seemed to help, eliminate the longer spells of cold water into maybe 30-45 second intervals and by increasing temp at the faucet it immediately would give more hot water (another weird problem) until it would ultimately get scalding hot when it did come back. Then it was the water flow switch that was suggested to change and then finally the exchanger. All provide marginally better performance for a few days but then back to the cycling of hot cold, which is where I am now

It has never had a problem getting hot or reaching a high temp. Just sustaining.

These Laars units came with a flow restrictor that needed to be piped in properly. They are hard to see on the piping because they sweat inside a fitting so you only see a little bit of the shoulder, I believe it's brass. If it's missing it would explain your problem and if its piped incorrectly it could also explain your problem. Take some pics and post them.

I think your problem is in your Mixing valve. The model you have is a tempering valve. You really need a thermostatic mixing valve.

If you want to test this, run the shower and go to the valve. As the temp from the boiler drops, the mixed temp to the house should stay the same. If they both drop at the same rate the valve is not doing it's job.

Carl

"If you can't explain it simply, you don't understand it well enough"Albert Einstein

So if you did change the honeywell mixing valve already once and the problem sort of got better then failed again, I am sticking with the lack of flow restrictor. To test run something like a bathroom faucet for as long as it takes to typically get it to fail. If the one fixture stays hot that helps us pinpoint, then turn on other fixtures until it fails. That boiler should be able to handle 4 faucets or 1 shower and 1 or 2 faucets simultaneously.

It shows the piping and tempering valve yours is done according to the manufacturer, so thats good. The only thing we can't see is the flow restrictor on yours. You need to make sure its there and before the mixing valve on the cold supply.

I think the water is passing through the heat exchanger to quickly due to the lack of the flow restrictor.

Firstly, Thank you all for your questions, suggestions and insight. It makes complete sense that so many turn to guys like you when they reach a dead end. Zman/Tom I think we are onto something!

So - the flow restrictor should be on the cold in to the mixing valve correct? I've rotated the pic of where it should be, sorry iphone for some reason made all the pics sideways.

The cold in line is at the rear in the pic. There is a shut off valve (which looks like it does in the picture in the manual) and then an elbow and the t for the valve itself. Could it be anywhere else? Or is it just missing???

Zman - with regard to the mixing valve - would you suggest a particular unit that is relatively cheap to try? The watts run about 30 bucks at home depot - but i do understand the get what you pay for. I guess if I'm cutting and sweating a flow restrictor in maybe I try a new mixing valve too?

Just a little confused - if I shut off the cold and run the shower and it stays hot then that would mean the mixer is not working? Or is it because I shut off the cold and "self restricted" - it means I need the flow restrictor? Sorry for being a little dense here but want to understand how the cold in impacts one more than the other

The mixing valve that you should be using at the boiler should be ASSE 1017 approved to be code compliant (the EBT 110 is not). A Watts 1170 would work. As well, the installation instructions do show a flow control fitting on the cold inlet. You should contact Laars to find out where to get one.

So I head home after work ready to isolate this problem thanks to all of you and what happens? Perfect shower. Perfect faucet. I don't get it.

The only differences compared to a normal day. I ran two faucets on hot and monitored temp to see if I could replicate before I shut off cold to test. Wouldn't work. So then headed up to the shower to try that. Normally my wife gives the baby a bath before showering but not tonight. In any case, hopped in the shower it was fantastic not a single drop in temp. Same for my wife. I just don't get this thing.

Not sure if this makes it lean more towards a mixing valve issue vs flow restrictor - but it certainly beats the hell out of me....sorry guys just need to vent no pun intended

So poking around and playing with the sensors I was able to replicate the F4 error by unplugging and plugging in the supply sensor. The other sensors threw different codes. Going to try and find a supply store open now and grab the mixing valve and the supply sensor and do them both. Hopefully it solves all the problems?

Ok tested the sensors and they are all in range. Based on what the laars techs say I either need a new circulator pump or the coil is scaled.

Went home to check it out and saw another f-4 on a call for hot from the laundry washer. Watched the boiler temp while wife was in the shower and noticed it start to climb hit 220 heard a clank and then it dropped back down but no f4. Not sure if this makes it sound like more of one than the other. Then on the next few fires it would climb to about 190-200 and then settle down no more clank/bang sound. Interested to hear what you think I should do next. Not looking forward to dropping another 200 plus time for a pump to figure out my coil is f'd. Got about 400 in parts and about 4-5 days of my time into it so far.

Also installed the flow restrictor too. Works great but still having soft lockout. Ugh!

You can amp your circ pump by pulling a wire out that connects to the pump and putting an amp probe around it to make sure its in range while running. All of these F4's I have seen have all been the sensor, you may be able to remove it and see its covered with scale like build up or it may just be shorting internally. I would change that and see how it goes. The circ is a bit of a pain and a bit costly.